Contrast-enhanced ultrasound versus color duplex ultrasound imaging in the follow-up of patients after endovascular abdominal aortic aneurysm repair

Abstract

This study assessed the negative predictive value, sensitivity, specificity, and diagnostic accuracy of real-time contrast-enhanced ultrasound imaging (CEUS) in the detection of endoleaks in patients with abdominal aortic aneurysm (AAA) who underwent endovascular repair (EVAR) compared with unenhanced ultrasound imaging. Computed tomography angiography (CTA) was the gold standard. The secondary objective was to define the optimal dose of the second-generation contrast agent to routinely use in the CEUS examinations for endoleak detection. The study enrolled 84 patients with unruptured AAA who were treated with EVAR and underwent CTA follow-up. In the same day, CTA (4- x 1-mm collimation, 1.25-mm slice width), unenhanced US imaging and CEUS imaging was performed in all patients. The CEUS studies were performed after an intravenous bolus injection of 1.2 mL and 2.4 mL of a second-generation contrast agent with continuous low-mechanical index (range, 0.01-0.04) real-time tissue harmonic imaging. The unenhanced US and CEUS studies were interpreted separately by two independent experienced readers to detect the presence of endoleaks by viewing recorded videotapes according to a five-point confidence scale. The standard of reference was represented by the consensus reading of CTA performed by two experienced radiologists not involved in the image analysis. Qualitative analysis as well as sensitivity, specificity, negative predictive value, and diagnostic accuracy in detecting endoleaks of each reading session were compared. CEUS imaging significantly improved the diagnostic performance of unenhanced US studies in the detection of endoleaks in terms of sensitivity (97.5% vs 62.5%), negative predictive value (97.3% vs 65.1%), accuracy (89.3% vs 63.1%), and specificity (81.8% vs 63.6%). The optimal dose of contrast agent to detect and characterize endoleaks was 2.4 mL. No adverse events were recorded during the study. The results showed CEUS imaging is a fast, noninvasive, reliable, and valid alternative to multislice CTA for endoleak detection in endovascular aortic stent graft patients, and is superior to unenhanced US imaging. Contrast-enhanced ultrasound imaging should be performed using a recommended contrast medium dose of 2.4 mL.